摘要
将煤焦油沥青基中间相炭微球(MCMB)在一定的工艺条件和不同最高热处理温度(HTT_(max))下进行高温热处理,利用XRD和Raman光谱分析了不同HTT_(max)下MCMB试样的微观结构。借助恒电流充放电和粉末微电极循环伏安法考察了试样的宏观电化学性能,探讨了中间相炭微球宏观电化学性能与其微观结构间的联系。研究表明,随着HTT_(max)的升高,中间相炭微球从低温热解炭的结构特征向石墨晶体结构转变,材料的电化学贮锂机制相应地也从微孔贮锂向石墨层间嵌锂机制转变。MCMB特殊的弧状碳层走向使得石墨微晶的L_a值未能随HTT_(max)的升高而大幅度增长,这是高温热处理MCMB的宏观电化学性能随HTT_(max)的升高而不断提高的内在原因。
Coal-tar pitch based meso-carbon microbeads(MCMB) were heat-treated with a certain technology under different maximum heat-treatment temperatures(HTTmax). Microstructure parameters of the heat-treated samples were characterized by XRD and Raman spectroscopic studies. Electrochemical performances of the samples used as the negative electrodes in lithium ion secondary batteries were examined through galvanostatic and cyclic voltametry measurements. Correlation between microstructures and electrochemical performances for MCMB was discussed. The results reveal that with increasing HTTmax, mi-crostructure characteristics of the MCMB undergo a structural transition from pyrolytic carbon to artificial graphitic carbon. Accordingly, the lithium ion storage mechanism of the electrode exhibits a transition from pin-pore storage to lithium insertion between carbon layers. The crystalline size along a axis (La) of MCMB does not greatly increase when being heat-treated due to the peculiar arc arrangement of carbon layers in MCMB. The appropriate La value of the MCMB obtained under extremely high temperatures is the internal reason for its excellent electrochemical performances.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2003年第9期1666-1670,共5页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:29973009)
河南省优秀中青年骨干教师基金
